An Israeli political scientist's study of a particular aspect of Israeli-Syrian relations: the way in which the two governments, by signals transmitted through public statements and through a third party (the United States), worked out a practical system of mutual deterrence based on "red lines" that were generally understood but subject to change over time and never specifically defined. He is naturally more surefooted on the Israeli than on the Syrian side of the story, but there is no doubt of the authenticity either of his account of how the system developed or of his conclusions.